Divinity doesn't mean much to these people, if you catch my drift. Bahamut isn't lord of everything, just Eos.

[ so it makes sense, in noctis' mind, that if he only rules eos, that his powers don't apply here. when somnus asks after the ring, noctis raises a hand to it - it hands from his neck on a chain. the weight of it on his finger felt too much to bear with no power behind it. ]

Me. It's powerless as well, same as the sword.

[ after a moment, wry, noctis shakes his head. ]

But I still have the power of Light; just not ours.